1. Field of the Invention
The present invention relates to a circuit for reproducing a picture image signal recorded on a video tape, more particularly, to a motion adaptive picture image reproduction circuit for adaptively reproducing a brightness signal of a picture image signal foldly recorded on a video tape to a corresponding motion. That is, the present invention relates to an apparatus for enhancing image quality of a video tape recorder using motion adaptive method which appropriately unfolds the brightness signal of a still picture image signal foldly recorded on the video tape and, otherwise, outputs the brightness signal of a picture image signal unfolding recorded corresponding to motion without any processing thereof.
2. Description of the Prior Art
In order to increase a resolution of a video cassette recorder (VCR), a conventional technique has been proposed in, for example, U.S. Pat. No. 5,113,262 filed by SAMSUNG Co. Ltd., on Aug. 17, 1990 which records a full bandwidth of television signal on a recording medium having a restricted bandwidth by folding high frequency component of the brightness signal on low frequency component thereof.
In this patent, the high frequency component of the brightness signal is modulated by a folding carrier, so that the folded brightness signal has a phase difference of 180 degrees between frames, scan lines and pixels, respectively. Therefore, when the high frequency component of the brightness signal folded on the low frequency component is reproduced, the high frequency component is demodulated by an unfolding carrier having the same phase and frequency as those of the folding carrier. Thus, the brightness signal of the picture image signal is unfolded to obtain a signal having the full frequency bandwidth.
According to the above-mentioned technique, however, all of the brightness signal are foldly processed regardless of whether a picture image is a dynamic picture or a still picture. As a result, a resolution of the picture image is deteriorated.
To solve the above problem, Korean Patent application No. 91-10836 filed by applicant has been proposed a recording technique, in which a folding manner of the brightness signal is changed in accordance with an amount of motion signal detected from a composite picture image signal such as a standard TV signal.
In this application, when the motion is detected from the brightness signal, the signal is considered as a dynamic picture image not to be subjected to the folding process. Alternatively, when no motion is detected from the brightness signal, the signal is considered as a still image to be subjected to the folding process.
More particularly, the proposed the adaptive processing method in which the motion detected from a TV signal applies the TV signal having a motion picture image to a conventional brightness processing portion of a video cassette recorder (VCR) and processor the TV signal having a motionless picture image by folding a high frequency component of the brightness signal onto the low frequency component thereof. The motion signal of the brightness signal, changed along the time axis, is recorded together with the folded brightness signal and a color signal so as to provide the recorded signal as a control signal in case that the brightness signal is unfolded in a full frequency bandwidth upon reproduction of the picture image recorded on the tape.